In the production of tubular elements it is known to wind an elongate strip of material in a helix on a core of very great length; often successive layers of different strip material are wound to form the body of the tubular element: this process can be used in forming both rigid or flexible tubular elements, but is particularly suitable for the latter, and the elongate strip material used may have different characteristics depending on the characteristics which it is desired to obtain for the tubular elements to be formed.
The strips must be wound on the cores with a cylindrical helical conformation and one technique currently used to achieve this is to rotate the core about its axis whilst the strip is delivered from a flat coil which is caused to travel longitudinally alongside the core itself. To obtain a finished product of high quality it is necessary that the strip be wound on the core with the maximum precision and with rigorous constancy of the winding pitch so as to avoid both overlapping of adjacent turns and the occurrence of spaces between adjacent turns. The former occurs if the pitch is too short, in which case there is an unwanted overlapping of adjacent turns of the strip, whilst if the pitch is too long there would be a spacing between adjacent turns of the strip causing in each case unwanted variations in the thickness of the finished tubular element.
With current techniques the application of the various layers of strip is effected entirely manually by means of an operator who is placed alongside the rotary core and utilising only his own ability and experience, controls the speed of advance of the strip-delivery carriage as the strip is drawn off by the core itself during its rotation. This work is extremely repetitive, very monotonous and extremely tedious for the operator and, inevitably, because the quality of the finished produce depends entirely on the concentration and ability of the operator, a uniform quality is not always obtained.
Various attempts at automation of such systems have been tried in the past without success because it has not been possible to match the exact speed of translation of the strip-delivery carriage along the axis of the core with the required speed at any instant, thus causing a non-uniform winding of the strip.